Exploring Expect

The -d Flag

The -d flag causes diagnostics to be printed out that describe the internal operation of Expect. Do not read too much into this—the diagnostics are not a systematic means for debugging. Rather, it is an accumulation of tiny windows that have been carved into various places in Expect, enabling you to see what is going on without too much effort.

The -d flag does not change the behavior of Expect. Nonetheless, it can provide extremely enlightening information, especially with respect to pattern matching. This information is further described in Chapter 7(p. 161).